In many industrial fields for the production of rolls of wound web material, logs of significant axial dimensions are produced, and are subsequently cut into smaller rolls, i.e. into rolls of smaller axial dimension destined for packaging and selling. Typical examples of this kind of processing are in the field of tissue paper converting, for producing rolls of toilet paper, kitchen towels and the like. In this field, plies of cellulose material are produced by means of continuous machines and wound into so-called parent reels. These reels are then unwound and rewound in rewinding machines, to form logs, whose axial length corresponds to the width of the ply produced by the paper mill and is equal to a multiple of the axial length of the products to be marketed.
Then, cutting machines are used to divide the logs into rolls of smaller axial dimensions, destined for packaging and consumption. Examples of cutting machines of this type are described in U.S. Pat. No. 6,786,808 and U.S. Pat. No. 5,522,292. The cutting machines for logs of wound web material, especially tissue paper, typically comprise a feeding path for the logs to be cut and a cutting head arranged along the feeding path. The cutting head comprises one or more disc-shaped cutting blades, that rotate around their axis and are also provided with a cyclical movement—for example, rotating or oscillating movement—to cut sequentially the logs of greater axial dimensions, fed along the feeding path, into single subsequent rolls.
The disc-shaped cutting blades are subject to wear and therefore require to be often ground. When it is ground, the disc-shaped cutting blade is gradually eroded, with a consequent reduction of the diameter thereof. When the minimal diameter dimension is achieved, the disc-shaped cutting blade shall be replaced.
When a disc-shaped cutting blade is replaced with a new disc-shaped cutting blade, it is necessary to adjust the position of the grinding wheels, moving them towards the new disc-shaped cutting blade, that has a diameter different (greater) than the diameter of the worn disc-shaped cutting blade that has been replaced. This operation requires long times and is particularly complex. It also requires the operator to access dangerous areas of the machine, where the disc-shaped cutting blade is arranged.
There is therefore a need for providing a machine for cutting logs of web material that overcomes or at least partially alleviates the drawbacks mentioned above.